计算：①2m²-m(2m-5n)-n(5m-n)②(3x-y)²-(3x+y)²-2xy③(m+1)(m+2)(m-1)(m-2)
问题描述：
计算：①2m²-m(2m-5n)-n(5m-n)②(3x-y)²-(3x+y)²-2xy③(m+1)(m+2)(m-1)(m-2)
④(x+1)²(x²+1)²(x-1)²
因式分解：①3分之4x²y³-9分之2x³y ②(x²+4)²-16x² ③16x的四次方-8x²y²+y的四次方 ④-5a³+5a
答
①2m²-m(2m-5n)-n(5m-n)=2m²-2m²+5mn-5mn+n²=n².②(3x-y)²-(3x+y)²-2xy=9x²-6xy+y²-(9x²+6xy+y²)-2xy=-6xy-6xy-2xy=-14xy.③(m+1)(m+2)(m-1)(m-2)=(m+1)(m-...